Camshafts

Engine temperature must be below 100°F (38°C). To facilitate the installation, make sure that No. 1 piston is at Top Dead Center before removing the camshaft.

Disconnect the negative battery cable.

Remove the valve cover.

Remove the distributor and the camshaft position sensor (if equipped).

Remove the timing belt. If necessary, remove the camshaft sprocket.

Remove the rocker arms, shafts and holders as an assembly (refer to the rocker arm removal and installation procedure in this section). To keep the assembly together, do not remove the cam holder bolts from the holes.

If the rocker shafts must be disassembled, use great care to catalog the position of each component. Each component, particularly the rockers, must be reinstalled in its original location.

Remove the camshaft from the cylinder head.

Fig. Fig. 1: After the rocker shaft assembly has been removed, the camshaft can be removed from the cylinder head

Fig. Fig. 2: Always discard the old oil seal

Inspect the camshaft, measuring the lobes and checking for any signs of wear or scoring. Check the journals as well as the lobes carefully.

To install:

Wipe the camshaft and the mounting surfaces. Lubricate the cam journals and mounting surfaces with a thin coat of assembly grease.

Fit the camshaft to the head with the keyway on the sprocket end facing upward.

Install a new camshaft oil seal with the spring end facing inward (towards the valves).

Lightly lubricate the cam lobes with clean engine oil.

Loosen the locknut and back off the adjusting screw for each rocker arm. Check the integrity of rocker assembly if it was disassembled. If the camshaft was replaced, it is strongly recommended that the rockers be replaced as well.

On 1986-95 Accords and 1985-95 Preludes, apply a liquid gasket sealant to the head mating surfaces of the outer cam holders.

Fig. Fig. 3: Apply a liquid gasket sealant to the head mating surfaces of the outer cam holders

Set the rocker arm assembly in place and install the bolts finger-tight.

Use a seal driver of the proper diameter and reach to seat the camshaft oil seal.

Tighten the bolts in the correct pattern two turns at a time (refer to the rocker arm procedures in this section). Keep a close watch to prevent the rockers from binding on the valves. Bring the bolts to final torque evenly and smoothly.

Install the camshaft sprocket if it was removed. Install the timing belt.

Install the distributor and the camshaft position sensor (if equipped).

Adjust the valve clearance. Reinstall the valve cover.

DOHC ENGINES

See Figures 4, 5, 6 and 7

Engine temperature must be below 100°F. (38°C). To facilitate the installation, make sure that No. 1 piston is at Top Dead Center before removing the camshaft.

Disconnect the negative battery cable.

Remove the valve cover.

Remove the distributor and the camshaft position sensor (if equipped).

Remove the timing belt. If necessary, remove the camshaft sprockets.

Loosen the rocker arm adjusting screws.

Unscrew the camshaft holder bolts two turns at a time using a crisscross pattern on non-VTEC engines. On VTEC engines, follow the loosening sequence in the illustration. Remove the holders from the cylinder head. Note the positioning of the holders (they are marked) so they may be installed in the same locations.

Fig. Fig. 4: Loosening sequence for VTEC engines

Remove the camshafts from the cylinder head.

Inspect the camshaft, measuring the lobes and checking for any signs of wear or scoring. Check the journals as well as the lobes carefully.

To install:

After cleaning the camshafts and journal surfaces, lubricate both surfaces with the assembly grease.

Position the camshafts in the cylinder head so the keyways are facing up (number one cylinder at TDC).

Install new camshaft seals with the open (spring) side facing in.

Apply liquid gasket to the head mating surfaces of the outer camshaft holders. Install the cam holders with the bolts finger-tight.

Fig. Fig. 5: Apply liquid sealant to the areas indicated

When installing the cam holders, note that each is lettered, numbered and marked with an arrow. Each holder MUST be put in the correct location.

Make sure the oil seals are fully seated in the holders.

Tighten the holder bolts two turns at a time using the proper sequence. Refer to the illustration for the proper torque specification.

Engine temperature must be below 100°F (38°C). To facilitate the installation, make sure that No. 1 piston is at Top Dead Center before removing the camshaft.

Disconnect the negative battery cable.

Remove the distributor.

Remove the side and valve covers.

Fig. Fig. 8: Exploded view of the camshaft and holder assemblies

Remove the timing belt. If necessary, remove the camshaft sprockets.

Unscrew the bolts securing the camshaft holders two turns at a time using a crisscross pattern, then remove them from the cylinder head. Note the locations of the different sized bolts.

Remove the camshafts from the cylinder head.

Loosen the exhaust rocker arms adjusting screws.

Inspect the camshafts, measuring the lobes and checking for any signs of wear or scoring. Check the journals as well as the lobes carefully.

To install:

Make sure the rocker arms are properly positioned on the valve stems.

Advance the crankshaft 30 degrees from TDC to prevent interference between the pistons and valves.

Install new oil seals and rubber caps on the camshafts. Apply liquid gasket around the rubber caps.

Lightly lubricate the cam lobes with clean engine oil.

Position the camshafts on the cylinder heads. Position the rear camshaft on the cylinder head so that the cam is not pushing on a valve.

Apply liquid gasket to the endcaps of the camshaft holders. Install the camshaft holders and plates on the cylinder heads.

Fig. Fig. 9: Apply liquid gasket to the shaded areas of the holders

Apply clean engine oil to the threads of the bolts. Install the bolts and tighten them using the correct sequence. The 6mm bolts should be tightened to 9 ft. lbs. (12 Nm) and the 8mm bolts to 20 ft. lbs. (27 Nm).

Fig. Fig. 10: Torque sequence for the camshaft holder plates

If applicable, install the camshaft sprockets.

Set the camshafts and crankshaft to TDC.

Install the timing belt.

Adjust the exhaust rocker arms.

Install the side and valve covers.

Install the distributor.

INSPECTION

See Figures 11, 12, 13 and 14

The camshaft must be handled carefully; it will break if dropped or subjected to sharp impact.

Overhead camshaft engines are very sensitive to proper lubrication with clean, fresh oil. A worn cam may be your report card for poor maintenance intervals and late oil changes. If a new cam is required, order new rockers to accompany it so that there are two new surfaces in contact.

Degrease the camshaft using solvent. Clean all the oil grooves and passages.

The end-play or thrust clearance of the camshaft is measured with the camshaft installed in the head. To check the end-play:

Position the camshaft(s) in the cylinder head. Install the camshaft holders or rocker arm shaft/camshaft holder assembly (as applicable). Be sure the rocker arm adjusting screws are fully loosened.

Seat the camshaft(s) by prying it toward the distributor end of the head.

Set a dial indicator on the end of the camshaft. Zero the dial indicator against the end of the distributor drive, then pry the camshaft back and forth. Read the end-play; the service limit is 0.020 in. (0.5mm). On DOHC and V-6 engines, perform this for both camshafts. If the end-play is excessive, replace the camshaft, then remeasure. If it is still excessive, the head must be replaced.

Fig. Fig. 11: Use a dial indicator to measure the camshaft end-play

Remove the camshaft(s) from the cylinder head.

Using a micrometer or caliper, measure the height of all the lobes. Record the readings and compare them to the Camshaft Specifications Chart in this section. Any measurement beyond the stated limits indicates wear and the camshaft must be replaced.

Fig. Fig. 12: Use a micrometer to measure the lobe height

Mount the cam in V-blocks and set the dial indicator up on the round center journal. Zero the dial and rotate the camshaft. The run-out must not exceed the following:

1984-89 Accord and 1984-91 Prelude-0.0023 in. (0.06mm)

1990-95 4-cylinder Accord and 1992-95 Prelude-0.0015 in. (0.04mm)

Accord V-6-0.0011 in. (0.03mm)

If the run-out is excessive, replace the camshaft.

Fig. Fig. 13: A dial indicator can also be used to measure run-out

The clearance between the camshaft and its journals must also be checked. Clean the camshaft, the journals and the bearing caps of any remaining oil and place the camshaft in position on the head. Lay a piece of compressible gauging material (Plastigage® or similar) on top of each journal on the cam.

Remove the bearing caps (in the correct order) and measure the gauging material at its widest point by comparing it to the scale provided with the package. The clearance should not exceed the following: